A haptic device provides a tactile sense to a user by generating a vibration, a force, or an impulse in a digital device. That is, the haptic device provides a vibration, a motion, or a force to the user when the user controls an input device (for example, a joystick, a mouse, a keyboard, or a touch screen) of the digital device such as a game console, a mobile phone, or a computer. Thus, the haptic device transmits realistic information to the user, like computer virtual experience.
In general, haptic devices for haptic technology include an inertial actuator, a piezoelectric actuator, and an electro-active polymer actuator (EAP).
The inertial actuator includes an eccentric rotation motor (ERM) that vibrates using an eccentric force generated by a weight body connected to a magnetic circuit, and a linear resonant actuator (LRA) that maximizes an intensity of vibration using a resonant frequency generated by a weight body connected to a magnetic circuit and an elastic spring.
The piezoelectric actuator is a device that is driven in a form of a bar or a disk using an elastic body, around a piezoelectric device with a shape that instantaneously deforms by an electric field.
In relation to the piezoelectric actuator, among the existing haptic devices, there were published Korean Patent Publication No. 10-1603957 (entitled Piezoelectric Actuator, Piezoelectric Vibration Apparatus, and Portable Terminal), and Korean Patent Application Publication No. 10-2011-0118584 (entitled Transparent Composite Piezoelectric Combined Touch Sensor and Haptic Actuator).
The EAP is a device that is driven by providing repeated motions using an electro-active polymer film attached to a mass body, on the main principle that a shape thereof deforms by a functional group of a polymer backbone having a specific mechanism by external electric power.
Further, in addition to the above haptic devices, haptic devices using shape-memory alloys, electrostatic forces, or ultrasonic waves are being developed.
At an early stage of development, the haptic device was mainly applied to aircraft and fighter aircraft simulations, virtual reality experience films, and games. With the release of a touch screen mobile phone to which haptic technology is applied after the mid 2000's, the haptic technology has emerged and become familiar to individual users.
As described above, the haptic device is used in various electronic devices such as game consoles. Use of the haptic device is increasing in response to a growing user demand for accessing media using a complex method such as a tactile method or an olfactory method in addition to an audiovisual method.
In general, an existing haptic feedback providing method operates the haptic device in response to an event generated when a user controls a digital device, or an event generated in an application. That is, the haptic device is triggered by a predetermined event generated when the user interacts through a user interface of the digital device, or the event generated in the application (for example, an alarm). Like this, in general, an event-driven haptic feedback providing method that outputs a predefined predetermined haptic pattern in response to the generated event is used.
Another haptic feedback providing method provides a haptic feedback by continuously converting output audio data into data for haptic output. In this example, the output audio data is converted into the haptic data using an analog signal scheme or a fast Fourier transform (FFT) filter scheme.
The analog signal scheme drives a haptic actuator using an analog signal generated when outputting audio data as an input. The analog signal scheme has an overly fast response rate, is easily implemented as hardware, and is more effective for a case in which a driving frequency range of the actuator is varied.